Melt butter and mix with sugar (mix until fluffy). Add flour. Shape dough into little balls, about the size of large marbles. Preheat oven to 375 degrees. Poke a dent into each ball and fill with jam. Bake at 375 degrees on ungreased cookie sheet for 10 minutes. Can substitute other jams such as strawberry and grape. Makes about 2 1/2 - dozen cookies.